How is the most large-scale construction in the North Caucasus

Today, we will inspect the most ambitious construction in the North Caucasus. I will show you the most high-pressure hydroelectric station (619 m) in our country, plus it will also have the longest diversion tunnel. Its length is 14,254 meters.

But this is not all, it turns out that it will also have the largest bucket type turbines in Russia. By the way, after the Zaramagskaya HPP-1 is commissioned, it will reduce the electricity shortage in the Republic of North Ossetia-Alania from 80% to 30%.

The idea to build the Zaramag HPPs in these parts appeared in 1976. Then with varying success passed to the practice. Due to financing problems, the construction periodically stalled until it was in the safe hands of RusHydro.
2. Future Basin daily regulation. The volume of this structure, representing an artificial concrete "bowl" on the top of the mountain, will be 250 thousand.m³, maximum length - 235 m, width - 80 m, wall thickness - 17-22 m.
The launch of the Golovnaya HPP, the first of the Zaramagskaya HPP cascade, took place on September 18, 2009. Now this station is operating in peak mode, delivering the required power to the network during hours of maximum load consumption. Currently, in accordance with the dispatch schedule of loads, the inclusion is carried out once or twice a day. In the low-flow period, it operates several hours a day with a load of 7 MW at a flow rate of 31 m3 / s before the drawdown of the useful level of the reservoir.

In the future, it will work closely with the Zaramagskaya HPP-1 under construction. And so the Golovnaya hydroelectric station is designed to use the water pressure created by the dam, extinguish it and supply water to the free-flow diversion tunnel. Further, the water flowing through a conduit with a height difference of 630 m, as a result of such complex logistics, will flow to the turbines of the Zaramagskaya HPP-1.
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After the Head Hydroelectric Power Plant was commissioned, work on the diversion tunnel and the daily regulation basin continued with varying success. So, by the middle of 2013, 12 km of the diversion tunnel were completed, installation of sub-horizontal water lines and mine facing was started,surface conduit construction was completed by 90%. More actively undertook HPP-1 in 2015. Added money and construction began to gain momentum.
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In 2016, the installation of the facing of the vertical shaft was completed, intensive construction and installation work was carried out in the sub-horizontal conduits and on the site of the daily regulation basin (in particular, concreting of the bottom of the BSR was started). In 2017, the construction of the Zaramagskaya HPP-1 building was started, as well as the passage of the emergency spillway of the daily regulation basin.

And now, in 2018, I am on the spot with a blogger check, literally reporting directly to you from the fields. In general, the scope of construction, of course, impressive. To take and cut off part of the mountain - for the power engineers it turned out not to be a feat at all, at the moment the readiness of work on the daily regulation pool reaches more than 80%, on the construction of the hydropower plant itself more than 60%. They say that very soon Zaramagskaya HPP-1 will issue its first current. Let me remind you that the planned design capacity of the Zaramagsky HPP cascade (consisting of the Golovnaya HPP and HPP-1) is 352 MW, and together they will produce about 812 million kWh per year.
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Construction of HPP-1 is carried out near the village of Mizur.Zaramagskaya HPP-1 is a complex engineering structure, largely located underground. For example, the total length of the tunnels will be more than 20 km. The Zaramagskaya HPP-1 complex includes a diversion tunnel No. 2, a pressure station station (a daily regulation pool with an idle spillway, a water receiver, a steel-reinforced concrete pipeline, a vertical shaft, sub-horizontal water lines), a 330 kV power distribution station.
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The daily regulation pool (BSR) with a capacity of 144 thousand m³ (with a NPU of 1,635.58 m) is intended for the accumulation of water before it is supplied to hydroelectric turbines. From himself he will be a concreted bowl with a maximum depth of 9.8 m, with massive walls, at the base of which is a gallery for diverting filtration costs and accommodating instrumentation equipment. The mark of the normal retaining level of water in the BSR is 1,635.58 m, the forced retaining level is 1,641.8 m.
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The water intake is designed to supply water from the BSR to the water conduit. It will be equipped with a trash rack, as well as flat repair and emergency repair valves, which will be operated using a rope mechanism with a lifting capacity of 125 tons and a bridge crane with a lifting capacity of 50 tons.
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All major work takes place in difficult geological conditions. Builders had to constantly defeat the local rock. After each meter of penetration, after the rock was filled and blown up, it was necessary to quickly lower the formwork and proceed to the concreting of the structure. And then you will hesitate and the rock will fall. In fact, this is the highest aerobatics of mining.
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A free-flow diversion tunnel No. 2. It is designed to supply water to a pressure station station of a hydroelectric station, and it begins at the building of the Golovnaya Hydroelectric Station and ends at the daily regulation pool. Its design length is 14,262 m. This is a record figure for hydraulic tunnels in our country. The capacity of the tunnel will be 65 m³ / s. Water will pass it in just 50-80 minutes.

For the tunneling of this tunnel 8 faces were organized, the longest section (7635.9 m) is located between faces 5 and 6. The tunneling was completed at the end of 2015. If there is a second, then there is the first. Let me remind you once again, I'm talking about the whole Cascade of the Zaramagskaya HPPs. And so, just the derivational pressure tunnel No. 1 with a length of 678 m, serves to supply water from the intake reservoir to the units of the Golovnaya Hydroelectric Power Plant.
13. This is what the Derivational Tunnel-2 looks like before leaving for the BSR.
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Steel concrete turbine water conduit has an internal diameter of 4.4 m and a length of 602 m. After laying it was covered with soil to protect the concrete shell from external influences. Then it goes into a vertical shaft (reinforced concrete lining with metal lining) with a diameter of 3.6 m and a depth of 507 m.
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Vertical mine. It will supply water to the turbines of the Zaramagskaya HPP-1. Its depth is 508 m. By the way, the Vertical Mine is one of the most difficult stages in the construction of the Zaramagskaya HPP-1. The penetration of this object was completed in the early 2000s. In 2014, the installation of its facing began: the steel sides of a length of 6 m, a diameter of 3.6 m and a weight of up to 22 tons were lowered with the help of a special mounting device.

In total, the facing mass of the vertical conduit was 1,439 tons. Passed her builders in 2016. By the way, there are no analogues to this object in the post-Soviet space either. There is a fork in the lower part of the mine into two sub-horizontal tunnels with a diameter of 2.5 m and a length of 1012 m. In the final part of one of the conduits, an idle discharge is provided to the Ardon river, bypassing the hydroelectric turbines.
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19. Somehow this mine will look like upon completion of construction.
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21. And the views are awesome.
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There, in the distance, work is underway on the construction of an emergency spillway for the basin of daily regulation. It is important to foresee everything. So, in case of failure of valves at the Golovnaya HPP and HPP-1, the water entering the BSR is automatically drained through the diversion tunnel of water, just into the emergency spillway, which in turn releases water into the Baddon river bed. Its maximum throughput is 70 m3 / s, which exceeds the throughput capacity of the diversion tunnel.

This spillway consists of a vertical part (mine), a horizontal section, an exit portal. To prevent the destruction of the mountain slope, a springboard is provided at the end portion of the spillway. The stream of water falling from a great height turns into mist, thereby losing energy. The length of the vertical part of the spillway is 80 meters, the horizontal part - 540 meters.
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28. And now we have gone down to the construction site where the building of HPP-1 will be located.
29. Portal of the tunnel of the turbine conduit.
In the building of HPP-1, two vertical hydraulic units will be installed with the largest K-600-V6-341.2 bucket turbines in Russia (the K-461-B-332 turbines, then the K-600-B6-334.5 turbines were planned for the initial design). ), operating at an estimated head of 609 m.The diameter of the turbine impeller is 3.345 m, the nominal rotation frequency is 300 rpm. Water turbines drive two CB 685 / 243-20 hydrogenerators with a capacity of 173 MW each.
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31. At the end of construction, everything will look like this.
Bucket turbines are different from other hydraulic turbines in that the turbine impeller is not immersed in water, but rotates under the action of water jets from special nozzles. Therefore, bucket turbines lack elements such as a stator, spiral chamber, suction pipe. Instead of them, a steel casing is built, inside which the impeller and nozzles are placed. A distributor is mounted around the casing - a piping system that supplies water to the nozzles.
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The manufacturer of hydroturbines is the German company Voith Siemens Hydro Power Generation (the company’s representatives are always on site and help to arrange everything and set it right), the Novosibirsk plant PJSC NPO ELSIB is responsible for the hydrogenerators, the casing is made at the Baltic Shipyard (St. Petersburg). In order to ensure the possibility of a quick overlap of water supply to the turbines, the building of the hydroelectric power station will be equipped with pre-turbine ball valves with a diameter of 2 m, manufactured by Turboatom.
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34. The future gantry crane.It will be with a lifting capacity of 500 tons and is intended for assembly / disassembly of hydraulic units.
35. The machine hall will be 42.7 m long and 32.2 m wide.
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37. Installation of hydraulic turbine distributors.
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Electricity generation from the generators will be produced at 15.75 kV for two power transformers ТДЦ-230000/330-У1 with a capacity of 230 MVA, and from there to the gas-insulated switchgear of 330 kV. Electricity is planned to be delivered to the power system via two 330 kV transmission lines 30 km long to the Alagir substation.
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44. By the way, the HPP building itself will be designed in the national style, thanks to which it will harmoniously fit into the natural landscape of the Alagir gorge.
The water that worked on the turbines will be discharged through the diversion channel into the channel of Ardon, while the channel design provides for its interface with the derivation of the promising Zaramagskaya HPP-2.
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